//使用Queue接口——模拟商业街咨询摊位队列 （和queue.c一起编译）
#include<stdio.h>
#include<stdlib.h>  //提供 rand() 和 srand() 的原型
#include<time.h>    //提供 time() 的原型
#include "queue.h"  //更改 Item 的 typedef
#define MIN_PER_HR 60.0

bool newcustomer(double x);    //是否有新顾客到来？
Item customertime(long when);  //设置新顾客参数

int main(void)
{
    Queue line;
    Item temp;               //新的顾客数据
    int hours;               //模拟的小时数
    int perhour;             //每小时平均多少位顾客
    long cycle, cyclelimit;  //循环计数器、计数器的上限
    long turnaways = 0;      //因队列已满被拒的顾客数量
    long customers = 0;      //加入队列的顾客数量
    long served = 0;         //在模拟期间咨询过Sigmund的顾客数量
    long sum_line = 0;       //累计的队列总长
    int wait_time = 0;       //从当前到Sigmund空闲所需的时间
    double min_per_cust;     //顾客到来的平均时间
    long line_wait = 0;      //队列累计的等待时间

    InitializeQueue(&line);
    srand((unsigned int) time(0));  //rand()随机初始化
    puts("Case Study: Sigmund Lander's Advice Booth");
    puts("Enter the number of simulation hours:");
    scanf("%d", &hours);
    cyclelimit = MIN_PER_HR * hours;
    puts("Enter the average number of customers per hour:");
    scanf("%d", &perhour);
    min_per_cust = MIN_PER_HR / perhour;

    for(cycle = 0; cycle < cyclelimit; cycle++)
    {
        if(newcustomer(min_per_cust))
        {
            if(QueueIsFull(&line))
                turnaways++;
            else{
                customers++;
                temp = customertime(cycle);
                EnQueue(temp, &line);
            }
        }
        if(wait_time <= 0 && !QueueIsEmpty(&line))
        {
            DeQueue(&temp, &line);
            wait_time = temp.processtime;
            line_wait += cycle - temp.arrive;
            served++;
        }
        if(wait_time > 0)
            wait_time--;
        sum_line += QueueItemCount(&line);
    }

    if(customers > 0)
    {
        printf("customers accepted: %ld\n", customers);
        printf("  customers served: %ld\n", served);
        printf("         turnaways: %ld\n", turnaways);
        printf("average queue size: %.2f\n", (double) sum_line / cyclelimit);
        printf(" average wait time: %.2f minutes\n", (double) line_wait / served);
    }
    else
        puts("No customers!");
    EmptyTheQueue(&line);
    puts("Bye!");

    return 0;
}

//x是顾客到来的平均时间（单位：分钟）
//如果1分钟内有顾客到来，则返回true
bool newcustomer(double x)
{
    if(rand() * x / RAND_MAX < 1)
        return true;
    else
        return false;
}

//when是顾客到来的时间，该函数返回一个Item结构
//该顾客到达的时间设置为when，咨询时间设置为1~3的随机值
Item customertime(long when)
{
    Item cust;

    cust.processtime = rand() % 3 + 1;
    cust.arrive = when;

    return cust;
}